The correct option is
B Aquatic free living crustacean
Cyclops are predominantly free-living crustaceans in the subclass Copepoda and the suborder Cyclopoida, and feature a central, anterior eyespot. Cyclops filter-feed on algae and other microscopic material as they swim through the water column. Cyclops is one of the most common genera of freshwater copepods, comprising over 400 species. Together with other similar-sized non-copepod fresh-water crustaceans, especially cladocera, they are commonly called water fleas. The name Cyclops comes from the Cyclops of Greek mythology which shares the quality of having a single large eye, which may be either red or black in Cyclops.
Hence, the correct answer is (B)